Fat Graft. The Science behind It.

Fat grafting is a method used to speed up the healing of wounds in challenging conditions, both in animals and humans. It triggers a biochemical process that promotes the repair of soft tissues and has a positive effect on blood vessel formation. The process involves two main processes: vasculogenesis and angiogenesis. Grafting fat in small portions, no larger than 3mm in diameter, enhances the growth of new blood vessels. The inflammatory role in neovascularization is essential for the development of healthy granulation tissue. In fat grafting, tissue trauma triggers an inflammatory response, which activates the growth of new blood vessels. Platelets, macrophages, and bone marrow-derived mesenchymal stem cells (BM-MSCs) help stabilize pericytes on newly formed blood vessels. This review aims to provide a deeper understanding of fat grafting at the cellular and molecular level. The inflammatory process in grafts involves the adaptive immune system recruiting naïve peripheral T helper cells to suppress local tissue inflammation, releasing cytokines like TNF-α. This inhibits the differentiation of adipocytes, allowing preadipocytes to differentiate into adipocytes. TNF-α improves the angiogenic capabilities of adipose-derived stem cells (ASCs), promoting the formation of new blood vessels and small blood vessels in the graft. Lipoaspirate, a key component of neovascularization, comprises many cell types essential for neovascularization, including cellular building blocks and precursor cells. Adipose tissue is a readily accessible source of multipotent stem cells, potentially having the highest percentage of adult stem cells in the human body. ASCs play a significant role in promoting the growth of new blood vessels in fat grafting through local signaling, increasing the concentration of VEGF at the graft site. Fat grafting is a unique method of plastic surgery that involves injecting a graft without blood vessels into an injured area. This process triggers a healing cascade that supports the survival of transplanted cells and facilitates the formation of a new vascular network. The process involves inflammation, cellular elements of the harvested lipoaspirate, and the combined effect of inflammation at the recipient site and the transplanted fat from the donor. Inflammation activates bone marrow-derived mesenchymal stem cells (BM-MSCs) and monocytes, facilitating the movement of cells and division, resulting in the formation of blood vessels. The grafted lipoaspirate experiences hypoxia, triggering a cytokine response and the depletion of graft cells. This process enhances tissue viability and blood supply, promoting regeneration.